Checks if this duration is zero length.
!(p)
A {@code Duration} represents a directed distance between two points on
the time-line and can therefore be positive, zero or negative.
This method checks whether the length is zero.
@return true if this duration has a total length equal to zero
Checks if this duration is zero length. !(p) A {@code Duration} represents a directed distance between two points on the time-line and can therefore be positive, zero or negative. This method checks whether the length is zero.
@return true if this duration has a total length equal to zero